Would you believe there is biblical precedent? In the Gospel of John, Jesus finds himself repeatedly in conflict with "the Jews," that is the educated, powerful ruling elite of his day. For them, his message is outrageous, impious, and dangerous. John records numerous confrontations between Jesus and these leaders. In the heat of one of them, "the Jews" say to Jesus,"Are we not right in saying that you are a Samaritan and have a demon?" (John 8:48, NRSV)
For these wealthy establishment types, Jesus was the Other—a lower-class, uneducated Galilean who challenged their power and their way of looking at the world. They responded to him in a number of ways including the charge that he was not "really" Jewish. He was not "really" one of them. As a despised Samaritan, he was their enemy and a faithless heretic. In this way, they could dismiss him and justify their disdain for him. It is interesting that they chose a racialist approach, one that removed Jesus from the race of God's people, the Jews, and reassigned him a place in the devil's race, the Samaritans.
Birtherism, in sum, is the reinvention of a very old wheel.